text: /* x-list.c
  
     Copyright (c) 2002 Apple Computer, Inc. All rights reserved.
  
     Permission is hereby granted, free of charge, to any person
     obtaining a copy of this software and associated documentation files
     (the "Software"), to deal in the Software without restriction,
     including without limitation the rights to use, copy, modify, merge,
     publish, distribute, sublicense, and/or sell copies of the Software,
     and to permit persons to whom the Software is furnished to do so,
     subject to the following conditions:
  
     The above copyright notice and this permission notice shall be
     included in all copies or substantial portions of the Software.
  
     THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
     EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
     MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
     NONINFRINGEMENT.  IN NO EVENT SHALL THE ABOVE LISTED COPYRIGHT
     HOLDER(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
     WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
     OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
     DEALINGS IN THE SOFTWARE.
  
     Except as contained in this notice, the name(s) of the above
     copyright holders shall not be used in advertising or otherwise to
     promote the sale, use or other dealings in this Software without
     prior written authorization. */
  
  #ifdef HAVE_DIX_CONFIG_H
  #include <dix-config.h>
  #endif
  
  #include "x-list.h"
  #include <stdlib.h>
  #include <assert.h>
  #include <pthread.h>
  
  /* Allocate in ~4k blocks */
  #define NODES_PER_BLOCK 508
  
  typedef struct x_list_block_struct x_list_block;
  
  struct x_list_block_struct {
      x_list l[NODES_PER_BLOCK];
  };
  
  static x_list *freelist;
  
  static pthread_mutex_t freelist_lock = PTHREAD_MUTEX_INITIALIZER;
  
  static inline void
  list_free_1 (x_list *node)
  {
      node->next = freelist;
      freelist = node;
  }
  
  X_EXTERN void
  X_PFX (list_free_1) (x_list *node)
  {
      assert (node != NULL);
  
      pthread_mutex_lock (&freelist_lock);
  
      list_free_1 (node);
  
      pthread_mutex_unlock (&freelist_lock);
  }
  
  X_EXTERN void
  X_PFX (list_free) (x_list *lst)
  {
      x_list *next;
  
      pthread_mutex_lock (&freelist_lock);
  
      for (; lst != NULL; lst = next)
      {
          next = lst->next;
          list_free_1 (lst);
      }
  
      pthread_mutex_unlock (&freelist_lock);
  }
  
  X_EXTERN x_list *
  X_PFX (list_prepend) (x_list *lst, void *data)
  {
      x_list *node;
  
      pthread_mutex_lock (&freelist_lock);
  
      if (freelist == NULL)
      {
          x_list_block *b;
          int i;
  
          b = malloc (sizeof (x_list_block));
  
          for (i = 0; i < NODES_PER_BLOCK - 1; i++)
              b->l[i].next = &(b->l[i+1]);
          b->l[i].next = NULL;
  
          freelist = b->l;
      }
  
      node = freelist;
      freelist = node->next;
  
      pthread_mutex_unlock (&freelist_lock);
  
      node->next = lst;
      node->data = data;
  
      return node;
  }
  
  X_EXTERN x_list *
  X_PFX (list_append) (x_list *lst, void *data)
  {
      x_list *head = lst;
  
      if (lst == NULL)
          return X_PFX (list_prepend) (NULL, data);
  
      while (lst->next != NULL)
          lst = lst->next;
  
      lst->next = X_PFX (list_prepend) (NULL, data);
  
      return head;
  }
  
  X_EXTERN x_list *
  X_PFX (list_reverse) (x_list *lst)
  {
      x_list *head = NULL, *next;
      
      while (lst != NULL)
      {
          next = lst->next;
          lst->next = head;
          head = lst;
          lst = next;
      }
  
      return head;
  }
  
  X_EXTERN x_list *
  X_PFX (list_find) (x_list *lst, void *data)
  {
      for (; lst != NULL; lst = lst->next)
      {
          if (lst->data == data)
              return lst;
      }
  
      return NULL;
  }
  
  X_EXTERN x_list *
  X_PFX (list_nth) (x_list *lst, int n)
  {
      while (n-- > 0 && lst != NULL)
          lst = lst->next;
  
      return lst;
  }
  
  X_EXTERN x_list *
  X_PFX (list_pop) (x_list *lst, void **data_ret)
  {
      void *data = NULL;
  
      if (lst != NULL)
      {
          x_list *tem = lst;
          data = lst->data;
          lst = lst->next;
          X_PFX (list_free_1) (tem);
      }
  
      if (data_ret != NULL)
          *data_ret = data;
  
      return lst;
  }
  
  X_EXTERN x_list *
  X_PFX (list_filter) (x_list *lst,
                       int (*pred) (void *item, void *data), void *data)
  {
      x_list *ret = NULL, *node;
  
      for (node = lst; node != NULL; node = node->next)
      {
          if ((*pred) (node->data, data))
              ret = X_PFX (list_prepend) (ret, node->data);
      }
  
      return X_PFX (list_reverse) (ret);
  }
  
  X_EXTERN x_list *
  X_PFX (list_map) (x_list *lst,
                    void *(*fun) (void *item, void *data), void *data)
  {
      x_list *ret = NULL, *node;
  
      for (node = lst; node != NULL; node = node->next)
      {
          X_PFX (list_prepend) (ret, fun (node->data, data));
      }
  
      return X_PFX (list_reverse) (ret);
  }
  
  X_EXTERN x_list *
  X_PFX (list_copy) (x_list *lst)
  {
      x_list *copy = NULL;
  
      for (; lst != NULL; lst = lst->next)
      {
          copy = X_PFX (list_prepend) (copy, lst->data);
      }
  
      return X_PFX (list_reverse) (copy);
  }
  
  X_EXTERN x_list *
  X_PFX (list_remove) (x_list *lst, void *data)
  {
      x_list **ptr, *node;
  
      for (ptr = &lst; *ptr != NULL;)
      {
          node = *ptr;
  
          if (node->data == data)
          {
              *ptr = node->next;
              X_PFX (list_free_1) (node);
          }
          else
              ptr = &((*ptr)->next);
      }
  
      return lst;
  }
  
  X_EXTERN unsigned int
  X_PFX (list_length) (x_list *lst)
  {
      unsigned int n;
  
      n = 0;
      for (; lst != NULL; lst = lst->next)
          n++;
  
      return n;
  }
  
  X_EXTERN void
  X_PFX (list_foreach) (x_list *lst,
                        void (*fun) (void *data, void *user_data),
                        void *user_data)
  {
      for (; lst != NULL; lst = lst->next)
      {
          (*fun) (lst->data, user_data);
      }
  }
  
  static x_list *
  list_sort_1 (x_list *lst, int length,
               int (*less) (const void *, const void *))
  {
      x_list *mid, *ptr;
      x_list *out_head, *out;
      int mid_point, i;
  
      /* This is a standard (stable) list merge sort */
  
      if (length < 2)
          return lst;
  
      /* Calculate the halfway point. Split the list into two sub-lists. */
  
      mid_point = length / 2;
      ptr = lst;
      for (i = mid_point - 1; i > 0; i--)
          ptr = ptr->next;
      mid = ptr->next;
      ptr->next = NULL;
  
      /* Sort each sub-list. */
  
      lst = list_sort_1 (lst, mid_point, less);
      mid = list_sort_1 (mid, length - mid_point, less);
  
      /* Then merge them back together. */
  
      assert (lst != NULL && mid != NULL);
  
      if ((*less) (mid->data, lst->data))
          out = out_head = mid, mid = mid->next;
      else
          out = out_head = lst, lst = lst->next;
  
      while (lst != NULL && mid != NULL)
      {
          if ((*less) (mid->data, lst->data))
              out = out->next = mid, mid = mid->next;
          else
              out = out->next = lst, lst = lst->next;
      }
  
      if (lst != NULL)
          out->next = lst;
      else
          out->next = mid;
  
      return out_head;
  }
  
  X_EXTERN x_list *
  X_PFX (list_sort) (x_list *lst, int (*less) (const void *, const void *))
  {
      int length;
  
      length = X_PFX (list_length) (lst);
  
      return list_sort_1 (lst, length, less);
  }
  